Three-layer single-phase winding



May 17, 1949. J. M. STEIN ErAr.

THREE-LAYER SINGLE-PHASE WINDING Filed Aug. 28, 1947 I l l l INVENTORS lesione.

ATTORNEY Patented May 17, 1949 THREE-LAYER SINGLE -PHASE WINDING Joseph M. Stein and Robert W. Egglestone, Buffalo, N. Y., assigncrs to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application August 28, 1947, Serial No. 771,044

(Cl. S18-221) 12 Claims. 1

Our invention relates to a line of single-phase capacitor-start squirrel-cage motors which uses the same frame-parts and stator-punchings as a corresponding line of poiyphase motors. In order to accomplish this purpose, it has been necessary to devise some sort of primary winding other than the concentric windings heretofore commonly used for single-phase motors.

Concentric single-phase windings have been used heretofore, for the purpose of producing a magneto-motive force With a minimum harmonic content, i. e., to produce an approximately sinusoidal ampere-turn distribution. The past practice, in winding single-phase motors, has been to use four diiferent sizes of coils, of successively smaller pitch, the successive coils having turnnumbers in the ratio 3:2.6:2:1, from the coil having the smallest pitch to the coil having the largest pitch.

A concentric winding necessarily has coils of a plurality of different pitches, and it also has a plurali-ty of different numbers of turns in each coil, making the winding-cost rather large. A concentric winding also involves long-end turns, which use up more copper and make the winding have a higher resistance. Other disadvantages of the concentric type of winding include the inability to wind the coils on simple automatic coilwinding machinery, the difficulty in placing the coils in the stator-slots due to the stiffness of the coils having the smallest pitch, and the relatively great bulk of the coil-extensions or endturns. Notwithstanding these disadvantages, the necessity for approximating a sinusoidal fluxdistribution has so far militated against the general use of any other kind of windings, other than the concentric windings, for single-phase motors.

Our new line of general-purpose squirrel-cage motors, designed with the specific purpose of achieving greater economies, by using the same parts for both polyphase and single-phase motors, as far as possible, has necessitated an abandonment of the previous practice of using concentric coils for the single-phase windings, because there simply was not room to use such windings.

It is an object of our present invention to `provide a three-layer lap-winding for single-phase motors, or a winding using preformed coils, all of which are identical with each other, i. e., all of which have the same pitch and the same number of turns in the coil. The pitch or chording is especially chosen, preferably having a value of two-thirds pitch, so that the completed main winding oi the motor will approximate a sinusoidal flux-distribution suiciently closely, by having one, two, or three main-winding coil-sides in the various slots, as needed, so as to approximate a sinusoidal ampere-turn distribution, such as 1:2:2:3:3:2:2:1, for the main winding.

A further object of our invention is to provide a starting winding which is similar to the main winding, except that it has a smaller number of coils, disposed in slots which do not have three .lain-winding coil-sides in them.

A differently stated object of our invention is to provide a novel kind of primary winding for single-phase motors, comprising main and starting windings which may be wound with automatic winding-equipment and resulting in a primary winding wherein some of the slots have two layers or coil-sides of main or starting windings therein, but wherein most of the slots have three windinglayers or coil-sides therein; the total bulk or volume occupied by the primary winding being such that the single-phase motor may utilize, in general, the same stator-punchings, and the same frame-parts and end-bells, as the correspondingly rated motors in a corresponding polyphase line of motors; thereby producing a single-phase motor which takes advantage of manufacturing economies resulting from the relatively large volume of business in the polyphase line of motors, while at the same time, achieving a reduced winding-cost for the single-phase windings.

With the foregoing and other objects in view, our invention consists in the machines, systems, combinations, parts and methods of manufacture operation, hereinafter described and claimed, and illustrated in the accompanying drawing, wherein:

Figure 1 is a developed diagrammatic representation of the main and starting primary Windings of a single-phase, one-H. P., fio-cycle, fourpole, W40-R. P. M. capacitor-start squirrel-cage motor, which is shown by way of example, and

Fig. 2 is a diagrammatic view of the motor, showing its terminal-connections.

The illustrated embodiment of a single-phase induction-motor includes a stationary primary member 40 and a rotor-member 4|. The rotormember is a squirrel-cage member, as shown in Fig. 2, having a squirrel-cage winding 42. It is mounted on a shaft t3 which carries a centrifugal switch dfi which is initially closed, but which opens, in response to the motor-speed, before the motor reaches its full speed during the startingoperation.

The stationary primary member, as shown in Fig. l., has a stator-core 45 having thirty-six winding-receiving slots therein, which are numbered consecutively from l to 36 in Fig. 1. The main winding M and the starting winding S have coil-sides which are disposed in the slots of the stator-core, as shown in Fig. l, the bottom or lowermost coil-side in each slot being the first or ieft-hand coil-side in the slot, as shown in Fig. 1, while the top coil-side is shown at the right-hand side of each slot in Fig. 1. The main-winding coils M are shown in full lines, in Fig. 1, While the starting-winding coils S are shown in dotted lines.

The mainwindingl lVIis preferably `a lap-wind. ing. It is icompo'sedl of coils which 'are all dehe tical with each other, and which all have the same pitch and the same number of turns per coil. A special feature of thevmainfwinding,isf

that it is a three-layer Winding, having one, two,

or three main-winding coil-sides in fthe: various slots, in such manner as to approximate'a sinus' oidal ampere-turn distribution? The starting-winding S is a similar Winding of smaller wire, with a smallerfnumberlofcoils,"

and more turns per coil, disposed in slots which do not have three main-Winding coil-sides in" them.

"' "'mate quite as closely to a sinusoidal ampere-turn ing-fto'fliinit*ourselves to any 'particular motor,"

it may be noted that th particularr motor which has"A been chosen for'- illustration of the' invention is a'ifourepole motor having 'thirty-six stator` slots,f-for' nine-stator-slots'per pole;v In 'this' particular motori' there are eight Y main winding: coils M 'per' poleghaving 23' 'turns perfcoil;I and there are* 4four starting-winding coils` Szper.' lpole, hayaV ingl` turns percOil..v The disposition .or arrange= S in-'fth'e'ivarious stator-'slots is shown in the fol? lowing tabulation :i

sloeNo i 2, 4 5 e 7 91 Location?l Y SSSS Iffwef'designate' the various slot'positio'ns' of the diffrent-Fcoilsi'des' by vamending*the letters" Cwand f T Tto the l number which: represents the esl'ot to .indicate :respectively 'the bottomr'iofrl thefslo't,""1 the center 'ofthe islotfand the top ofhand coil-side by the letters RH, the orderof windinglassembly of the primarywindings of our" illustratedmotorl Will`r be'as followsgf starting with thefstartirig-winding coil 4S vhavingfa fleFft-handv coil-side fLHtlyingiinithe-'bottom of sl'ot*l ,f which 'f is indicatedas I-G for "th `center of =the"slot,w because this- 'fis a slot' rhaving only :.-two coil-sides* therein, when the windingfis finished; and havi ing-naf-right-hand coil-sidelRfH in thefsbottomY-off Ornew'typeof winding, as just described, is provingverygsuccessful in anew'line of motors' in whichgreater economies are eected; in size,`

SSSS SS SS--.

distribution as was previously accomplished with concentricicoilsl having turn-ratios: of H1," 2, 2.6,-l

and experience .has shown: that our approxi;i

mation'fishsuiciently vclose so that our new `mo- M tori meets? al'lf of 'the fstandardl commercial irequirements for: motors of this class.

While'fall of iour-sta'tor'-slots are not-equally full, experience has shownthatthe;incomplete"-44 ly flled f'slots experience:v a shifting andre-ar# rangement ot1 wires in' them; and --no special llingris'aneededfto Vtake up unfilled lspaces.

Besides s all of itsv other advantages,` our1 new--L primary winding-is very much more 'economicalf-- to wind `than the `previously used concentric'wind-JI ings, riithe previous single-phase-motors of the type'towhich'ourfinvention applies.

n`"the'operation 'of kour motor,4 suitable ter-`- mina-l#connectionsareneeded'as1 partially' shown in Figf'lj andas`shown more in detailinFigxZ. Thitwo' supplyeline leads are "indicated "at *Ll and"L2-"in1`Fi'g: 2." The .line-'conductor LI =may,

be connected,f0rexample (for counterclockwise rotation ofthe motor), to the main-.winding ter.-V

mirialTVand' to the starting-winding terminalV T27 The` "otherstartingwinding Y terminalH TC mayjbe connected, as shown in Fig.2," to two serially connected electrolytic `capacitors Cl and C2,"' Whic'hare connected, through a terminal' connector' TS; to the centrifugal starting-switchv Mlgand thence to the 'starting-winding motore terminal T4," The second line-conductor L2 is4 connected to the mainewinding terminal T3 'and to the startingwinding terminal'T, .as shown in Fig. 2J

When power'is applied to the line-conductors LI and L2,"the motor starts as a two-pole -motor, by reason of the fact that the starting-Winde ingis spatially displaced inquadrature .phase-lv relation,;-with4 respect tothe mainwindingM,

while the current in thestartingfwinding isladf` vansed in time-phase, ,with respect. ,to .thercure rent/inthe main Windingr by: reason of the-ecapacitors Cl' and C2."v When the motor approaches suiiciently' closely'4 toward its full speed; the

starting-switch opens thereby disconnecting thestartinglwi'nding .S.so that the motor theref after 'continues .to pull upto speed, and operates thereafter," withonly .its main vwinding M ener:

gized." Tlzle,,starting#WindingjSV thus has. only a very 'briefntermittent duty to perform, ,and`

henceit is customaryjto` Wind the :startingWind-A s. ing S with less copper than the main winding M, and We have continued this practice in our present motor.

While we have illustrated our 'invention with reference tc a single illustrative motor, as being representative of an entire line of mctcrs of different ratings and pole-numbers and speeds, we wish it to be understood that our invention is not limited to the precise details which have been shown and. described. We desire, therefore, that our appended claims shall be accorded the broadest construction consistent with their language.

We claim as our invention:

1. A single-phase induction-motor having a stationary primary member and a rotor-nehmer, said stationary primary member having a slotted stator-core and main and. starting windings having coil-sides disposed in the slots of the statorcore; said main winding having coils which. are all identical with each other, all having the saine pitch and the same number of turns per coil, said main Winding being also a three-layer winding having one, two or three main-winding coilsides in the various slots in such manner as to approximate a sinusoidal ampere-turn distribution; and said starting winding being a similar winding of less copper, with a smaller number of coils, and different turns per coil, disposed in slots which do not have three main-winding coilsides in them.

2. A single-phase capacitor-start squirrelcage motor, as dened in claim 1, characterized by said rotor-member being a squirrel-cage member, and said starting winding being in a circuit which serially includes a capacitor-means and a starting-switch which opens before the motor attains its full speed during starting.

3. A single-phase self-starting squirrel-cage motor, as defined in claim 1, characterized by said rotor-member being a squirrel-cage men.- ber, and said starting winding being in a circuit which serially includes a phase-shifting means and a starting-switch which opens beiore the motor attains its full speed during starting; the number of stator-core slots being nine per pole, the main-winding pitch being two-thirds ci ruil pitch, the number oi main-winding coils being eight per pole, and the numbers of main-winding coil sides in successive slots, for any pole, being lJ 2, 2, 3, 3, 2, 2 and 1, respectively.

4. A single-phase self-starting sduirrei-cage motor, as dened in claim l, characterized by said rotor-member being a squirrel-cage member, and said starting winding being in a circuit which serially includes a phase-shifting means and a starting-switch which opens before the motor attains its full speed during starting; the number of stator-core slots being nine per pole, the main-Winding pitch being two-thirds of full pitch, the number of main-winding coils being eight per pole, the numbers of main-winding coil-sides in successive slots, for any pole, being l, 2, 2, 3, 3, 2, 2 and l, respectively; and the starting winding having two coil-sides :in each ci the stator-cere slots which has no main-winding coil-sides in it, and having one coil-side in each of the next three stator-core slots on each side of the slot having said two starting-winding coil-sides.

5. An element of a dynamo-electric machine having a slotted core, and a winding having a plurality of substantially identical coils, all spanning the same number of slcts and having substantially the same number of turns per coil, the coil-sides of said winding lyingr in said sicts in such manner that a winding-circuit has a graduated number of such coil-sides for each pole, with a minimum number at the edges of the pole, and a maximum number at the central part of the pole, said maximum number of Coilsides being greater than two.

6. The invention as dened in claim 5, characterized by the numbers of coil-sides of Said winding-circuit, for any pole, being 1, 2, 2, 3, 3, 2 2 and 1, respectively.

7. A single-phase induction-motor having a stationary primary member and a rotor-member, said stationary primary member having a slotted stator-core and main and starting windings having coil-sides disposed in the slots of the statorcore; said main winding being a lap-winding having coils which are all identical with each other, all spanning the same number of slots and having the same number oi turns per coil, said main winding being also a three-layer winding having one, two or `three main-winding coil-sides in the various slots, in such manner as to approximate a sinusoidal ampere-turn distribution; and said starting winding being a similar winding of smaller wire, with a smaller number oi coils, and more turns per coil, disposed in slots which do not have three main-winding coil-sides in them.

8. A single-phase capacitor-start squirrel-cage motor, as dened in claim 7, characterized by said rotor-member being a squirrel-cage member, and said starting winding being in a circuit which serially includes a capacitor-means and a starting-switch which opens before the motor attains its full speed during starting.

9. A single-phase capacitor-start squirrel-cage motor, as defined in claim 7, characterized by said rotor-member being a squirrel-cage member, and said starting winding being in a circuit which serially includes a capacitor-means and a starting switch which opens before the motor attains its full speed during starting; the number of statorcore slots being nine per pole, the main-winding pitch being two-thirds of full pitch, the number of main-winding coils -being eight per pole, and the members of main-winding coil-sides in successive slots, for any pole, being 1, 2, 2, 3, 3, 2, 2 and 1, respectively.

19. A single-phase capacitor-start squirrel-cage motor, as defined in claim 7, characterized by said rotor-member being a squirrel-cage member, and said starting winding being in a circuit which serially includes a capacitor-means and a starting-switch which opens before the motor attains its full speed during starting; the number of stator-core slots being nine per pole, the main-winding pitch being two-thirds of full pitch, the number of main-winding coils being eight per pole, the numbers of main-winding coil-sides in successive slots, for any pole, being 1, 2, 2, 3, 3, 2, 2 and 1, respectively; and the starting winding having two coil-sides in each of the stator-core slots which has no main-winding coil-sides in it, and. having one coil-side in each of the next three stator-core slots on each side of the. slot having said two starting-winding coil-sides.

11. An element of a dynamo-electric machine having a slotted cere, and a lap-winding having a plurality of substantially identical coils, all spanning the same number of slots and having substantially the same number of turns per coil, the coil-sides of said winding lying in said slots in such manner that a winding-circuit has a graduated number of such coil-sides for each pole, with a minimum number at the edges of the pole, and a maximum number at the central part oi thev polei, said. maximum number of ooi'i-sides. A 4 being; greater than: two; UNITED STATES PATENTS 12. The invention. as;l defined: in claim 11, Number Name Date, characterized by the numbers of coil-sides of 618,578 NEWCOmb @111.3111899 said winding-eireuit-,for any pole, being 1, 2, 2, 3, 5 FOREIGN. PATENTS 3, 2, 2 and 1, respectively.

JQSEPH. M STEIN Number Country Date ROBERT W EGGLESTONE, 34,838 France May 21, 1929 386,503 Great Britain Jan. 19., 1933 REFERENCES CITED 10,

The following references are of' record in the ie of this patent-r 

